We've refinished quite a few burned firearms over the years. First, just as FYI for firearms that have been in a house fire:
Even if they weren't physically burned, they've been exposed to all kinds of corrosive vapors and steam. That's a perfect environment for rust. The wood should be removed and soaked in a good quality wood furniture "rejuvenation" chemical. The metal parts should be disassembled or at least field stripped. Wash them in soap and hot water. Blow dry with compressed air or at least a hair dryer. Then spray them all down heavily with WD40. Yes, it's a lousy lubricant but it's a great water displacer. Determine if they can be safely restored. if so, soak them in an automotive oil and leave them "wet". We've had firearms arrive here that were wrapped in oil soaked rags inside plastic bags. They were dripping with oil when I unpacked them but that's the best way to protect them.
To determnine if they can be safely restored: Note: "Safely restored" means doing it without re-tempering the metal. Re-tempering isn't cheap so it may not be worth it to have that done.
I break it down into three stages.
1...Rusty metal. That's not a real problem as long as you get to it before pitting sets in.
2...Burned wood. If the wood is actually charred, then it was on fire. The temperatures for wood ignition vary quite a bit depending on a lot of variables but generally, it has to be in excess of 200 Centigrade. This is high enough to start to temper some metals so charring is not a good sign.
3..."Dead" springs. Springs are made from tempered steel. Their mass compared to their size is usually quite small. That means that they get hot and cool down fast and that means that they will loose their tempering fast. If the springs have no spring left, the whole thing was subjected to excessive temps. At that point, I would write it all off. Either make it a wall hanger with a disabled firing mechanism or scrap it for the small parts.
A word of caution! Some shops that refinish firearms have the equipment and ability to test the hardness of the metal. Most, including us, don't. Some shops will refuse to refinish burned firearms because of the questions regarding heat treating. Some shops don't care and will refinish it even if the metal is as soft as putty! We have a simple policy:
If the wood is charred, it
might be dead.
If the springs don't spring anymore, it is most certainly absolutely without a doubt dead as far as we are concerned. If
I'm not sure about, it won't get refinished by us. Yes, it might not be really dead but we're not taking the chance that it comes apart in your face.
Here's some photo's of burned rifles to look at. The damage to these rifles was all caused by smoke, steam and corrosive fumes. Keep yer powder dry, Mac.
Before.
http://www.shootiniron.com/P1010032.jpg
http://www.shootiniron.com/P1010045.jpg
After
http://www.shootiniron.com/PA080010.jpg
http://www.shootiniron.com/PA080008.jpg
Tuff-Gun Finishes. The Name Says It All.
Mac's Shootin' Irons.
http://www.shootiniron.com